1. Technical Field of the Invention
This invention relates to optical interconnection apparatus (optical circuit board) for mutually connecting optical component, parts and/or devices used in optical communications or optical information processing, such as optical components, optical circuit packs and optical circuit devices.
2. Prior Art
To permit optical interconnections between plural optical components in an optical circuit pack or optical interconnections between plural optical circuit packs or between optical circuit devices on each of which optical packs are mounted, these optical components, optical circuit packs and optical circuit devices are provided at terminals thereof with optical connectors to interconnect them together via optical fibers. As these optical fibers have to be arranged with loose in this case, it is a current circumstance that, on an optical circuit pack or inside and/or on a back side of an optical circuit devices, intricately routed lines of the optical fibers extend overlapping one another in the form of a bird""s nest and hence occupy a large space. For an optical interconnection process which is complex and requires a large space as descried above, a proposal has been made, as a simple process anywhere routing of optical fibers on a two-dimensional plane as desired, to use a sheet or substrate with a pressure-sensitive adhesive coated thereon and to hold optical fibers in place by the pressure-sensitive adhesive as disclosed in JP 2,574,611 B.
Incidentally, the optical interconnection apparatus disclosed in JP 2,574,611 B is obtained in such a way that upon its fabrication, optical fibers are located by a pressure-sensitive adhesive, which is coated on a substrate (base layer) to form a routing pattern and the routing pattern is then covered with the same material as the material used for the substrate, whereby a protective layer is formed. This process is however accompanied by problems in that as optical fibers so located increase in number and the optical fibers increase more overlapped portions (cross-over routing) in the routing pattern so formed, the resulting routing layer of the optical fibers becomes thicker and, because the tacky surface with which the optical fibers are in contact becomes smaller at the overlapped portions of the optical fibers, the protective layer cannot be arranged evenly. There is a further problem in that at the overlapped portions of the optical fibers in the routing pattern, the fixing force by the pressure-sensitive adhesive becomes weaker and the optical fibers are allowed to move, thereby resulting in displacements in the routing pattern (a loss in the intactness of the routing pattern). Moreover, general optical fibers range from 125 to 250 xcexcm in diameter so that at an overlapped area of three optical fibers, for example, the routing layer of the optical fibers becomes as thick as 375 to 750 xcexcm. An increase in the overlapped portions of optical fibers in a routing pattern develops lifted portions (air pockets) in a protective layer around optical fibers underneath the protective layer, so that a problem arises in the reliability against temperatures and humidities and in addition, the optical circuit board becomes extremely weak to breakage which may be caused by deformation such as bending. Furthermore, since the film substrates are arranged on both sides of the two-dimensionally routed optical fibers, the optical interconnection apparatus has remarkably reduced flexibility and, hence, arrangement of extended tabs is needed upon interconnection of optical components themselves on an optical circuit pack or interconnection of optical circuit packs together. Therefore, when there is not much space for the arrangement of the optical interconnection apparatus, there is a problem that the optical interconnection apparatus cannot be used due to insufficient flexibility and bendability.
In order to solve these problems, it has been examined to fix the optical fibers extend overlapping one another by forming a resin protective layer on the optical fibers routed on an adhesive layer. In such a case, however, the optical circuit board as a whole has remarkably reduced flexibility, because the optical fibers serve as a reinforcing material in portions where the optical fibers are routed intricately with overlapped state and bendability of the optical fibers routed overlapped state, the substrate and the resin protective layer are different each other. Therefore, when there is not much space for the arrangement of the optical interconnection apparatus, there is the same problem as in the optical interconnection apparatus disclosed in JP 2,574,611B, that the optical interconnection apparatus cannot be used due to insufficient flexibility and bendability.
In order to solve the above-mentioned problems of insufficient flexibility and bendability, it has been attempted to fix and protect the routed optical fibers in a state of embedding in a resin protect layer of high flexibility without using a base film. In such a case, there is a problem that the optical interconnection apparatus has poor self-supporting ability, although their flexibility and bendability are high, and it becomes necessary to handle it with care due to difficulty of handling.
The present invention has been completed with a view to resolving various problems of the conventional art such as those described above. Described specifically, an object of the present invention is to provide a self-supporting optical interconnection apparatus which makes it possible to readily interconnect optical devices such as optical components, optical circuit packs and optical circuit devices, and has high flexibility and can be easily handled.
An optical interconnection apparatus according to the present invention comprises a base film having a two-dimensional plane and flexibility, plural optical fibers routed on at least one side of said base film, and a protective resin layer having flexibility by which said routed optical fibers are held in place and protected, said optical interconnection apparatus being characterized in that said base film has at least an opening so as to improve flexibility and bendability, and said optical fibers are held in place and protected in an embedded state in said protective resin layer without existence of the base film.
An optical interconnection apparatus according to a first embodiment of the present invention comprises a base film having a two-dimensional plane, plural optical fibers two-dimensionally routed on at least one side of said base film and provided at opposite ends thereof with end portions adapted to permit optical interconnections thereto, and at least one protective resin layer having flexibility by which said routed optical fibers are held in place and protected; wherein said optical interconnection apparatus is characterized in that said base film has at least an opening, and said optical fibers are fixed and protected by a protective resin layer in said opening in an embedded state.
An optical interconnection apparatus according to a second embodiment of the present invention has at least two flexible base films having a two-dimensional plane, which is characterized in that at least two optical interconnection apparatuses of the above-mentioned first embodiment are stacked to form a stacked structure.
According to the present invention, it is possible to improve flexibility of the optical interconnection apparatus, because the base film is not existent in the area where the intricately routed optical fibers having lower flexibility extend overlapping one another, and said optical fibers are held in place and protected in a form embedded in at least one of the protective resin layers having higher flexibility.
Namely, the optical interconnection apparatus of the present invention is easily handled, because a flexible base film is existent in the greater part of the apparatus, while the flexibility of the apparatus is remarkably improved, because there is no base film but a protective resin layer having larger flexibility in the area where flexibility becomes low because of the optical fibers being intricately routed or the area where flexibility is required for working. Accordingly, it becomes possible by using the optical interconnection apparatus of the present invention to easily achieve the attachment without damaging optical and mechanical properties of the optical interconnection device, when a large flexibility is required in a small space for arrangement of the optical interconnection device such as optical components, optical circuit packs and optical circuit devices.